Knockout of Hmox1, the gene that encodes HO-1, also partially rescues proliferation of pancreatic cancer cells deficient in hydroxymethylbilane synthase (Hmbs), implying that the dependency on heme synthesis may be partially caused by environmentally-induced upregulation of HO-1, resulting in increased heme degradation [29]. The gene discussed is HMOX1; the disease is familial pancreatic carcinoma.